Using the ATmega328 off of the Arduino

Hi All,

I have been prototyping simple ideas on my arduino for a little over a year now. I have been amazed by the wealth of information available on the arduino, and the help that I have received on my recent adventure. http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1286516320/0

My question is pretty simple. My idea for that post (it may not be necessary to read it) will be a permenant device that I will actually use. It just dawned on me that the microcontroller could be used on a circut board off of the Arduino. Most of the stuff that I haev built has been documented, and then torn down, because buying an arduino for each idea woulod be more costly than was justifiable.

Now, I can use the arduino for prototyping and building the circuts, programming the chip, testing, and so on. After that, I could use an ic socket on a circut board right? Are there any good recources on this website, or the net about doing this? I am assuming that there would need to be special things to look at or to consider when doing this. (Things like protection built into the arduino?). Most of my circuts are simple, using only a few digital pins.

I just purchased a second arduino so I can prototype on it, and burn bootloaders into raw 328 chips. If I could make this work, it may be feasible to keep some of my prototypes around that do not justify a whole Arduino.

http://itp.nyu.edu/physcomp/Tutorials/ArduinoBreadboard

Try the above tutorial. I did it and went on to make this:

http://picasaweb.google.com/101109833558680146619/StandalonePhotogatePCBSystem#5519227281217380050

Check this out: http://www.moderndevice.com/products/rbbb-kit

There's a schematic for it on that page.

All you really need for an Arduino is the microchip, a 5v regulated power source, (ie, a voltage regulator and two capacitors connected to a battery) a 16mhz resonator, and a .1uf capacitor for the reset line. And you can get by with even less than that if you know what you're doing.

You will need to get an FTDI programmer and chips preloaded with the Arduino bootloader from Sparkfun or make one of those other kinds of programmers I forgot the name of which let you burn a bootloader yourself to program it. But once you have that programmer you can just use the bare chips like on that barebones board.

That is awesome guys. Thanks for the great resources.

I had thought that this would be alot more complicated. I thought that there was going to be alot more circutry required.

also, check out this:

http://www.geocities.jp/arduino_diecimila/obaka/project-2/index_en.html

Is it necessary to have the 16mhz crystal? I have not found very good information on this.

It looks like the Atmega328 has an internal 8mhz oscillator? What are the implications of using this? I not not have any time-sensitive applications, but will that affect serial communication?

Is it necessary to have the 16mhz crystal?

An external crystal is not required but you will have to change fuse settings (you’ll need an ICSP).

It looks like the Atmega328 has an internal 8mhz oscillator?

It does.

What are the implications of using this?

You will have to use an 8 MHz board definition when Verifying (compiling).

I not not have any time-sensitive applications, but will that affect serial communication?

It may. Atmel guarentees ±10% on the internal oscillator. If the oscillator is too far from 8 MHz, serial communications will not be reliable and may not work at all. You can use the OSCCAL registor to tune the oscillator to ±1%.

This may help…
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1287558192

Thanks for the info. That is what I was hoping to hear. =)

I love Arduino!

Using an external crystal increases the part count by 3, 1 crystal and two capacitors. This would be a very good option considering the alternative of using the internal oscillator. A crystal plus the caps, will cost you less than USD1 if you buy in bulk (say 5-10).

You can get a ceramic resonator with the caps built in. It is a through-hole part that connects directly to the OSC pins of the AVR.

These are way better than the internal osc and easier to wire than the crystal and caps. Stronger against shock and vibration too. <$1 each in single quantity.

The internal osc can be calibrated but each CPU chip will have to be individually calibrated. Also the internal osc is fairly temperature sensitive so even if you calibrate it, the thing can drift a lot if the temp changes.

/me

Also the internal osc is fairly temperature sensitive so even if you calibrate it, the thing can drift a lot if the temp changes.

I agree with everything you said except that. From the '328 datasheet it looks like a 10°C band around room temperature has a swing of about ±0.3125%; which coincides with my observations. That hardly qualifies as "a lot". In addition, I've seen no evidence that the oscillator "drifts". At a given temperture / voltage, the calibration has always been very consistent.